Various data storage system include a disk mounted a hub attached to a spindle motor which rotates the disk assembly. The following description will refer specifically to hard disk storage systems also called hard disk drives (HDD), but the principles are applicable to other devices. In a hard disk storage system the disk is typically rotated at thousands of rpms. FIG. 1 is an isometric illustration of a prior art clamp 51 with screw holes 66 and a central bore 68 which is used in a disk drive to clamp a disk on a hub. The clamp 51 mates with a hub 53 which is shown in FIG. 2 in a section view. The hub has threaded holes (not shown) for screws which are inserted through the holes shown in the clamp 51. The screw holes in the hub and clamp arranged in generally circular pattern around a central axis of rotation. The disks (not shown) have a central hole to fit on the hub and are held on the hub by the clamp with threaded screws which engage the threaded holes in the hub. These screws as well as others in the drive fasten different parts by delivering load in axial direction, which is very sensitive to screw surface finish. In order to deliver consistent axial load, the screws are either coated with a lubricating metal such as nickel (Ni) or have a liquid lubricant applied to them. Liquid lubricant tends to deliver more consistent axial load. When tightening the Ni-plated screws, undesirable particles can be generated which will cause contamination problems. Lubricated screws with proper solvent generate less particles. However, lubricated screws create a problem since the liquid lubricant can be mobile and tend to migrate across the spinning disk. Lubricant migration is obviously not desirable and could cause head-disk interface problems.
U.S. Pat. No. 6,417,988 to Renken, et al. describes a clamp for a disk. The disk assembly includes an annular disk clamp having a central aperture having a middle annular raised portion, an outer annular periphery portion, and at least one inner centering portion including an inner vertical peripheral surface. The central aperture of the disc clamp is sized to receive the spindle to allow the inner centering portion to center the disc clamp about the spindle, while the outer periphery engages the top surface of the information storage disc, and the middle annular raised portion extends above the top surface of the hub portion and is adapted to receive a downwardly directed force. A disk clamp retainer applying this force is connected to the spindle. The disk clamp retainer is fastened to the spindle and engages the middle annular raised portion of the disk clamp to transmit this force through the outer peripheral portion to the disk.
In U.S. Pat. No. 6,724,568 to Suwito, et al., a clamp for securing data storage disks to a hub of a disk drive mechanism is described which includes a flat body with a protuberance that defines a flat distal surface for engaging a data storage disk. The body also includes bores that receive members for securing the clamp to the hub and at least one groove for distributing the securing force of the securing members.